Servomotor for the remote control of aircraft



`Nov. 7, 1'939. E, FlcHx-:L ET'AL 2.179.179 i SERVOMOTOR FOR THE REMOTE CONTROL OF AIRCRAFT Filed Nov. 24, 1957 Patented Nov. 7, 19239 UNITED STATESy PATENT OFFICE- sEnvoMo'ron Fon. 'run ooN'moL l c or l Application November 24, 1937;"Serial No.176,385

In Germany Novemberg, 19u36 12 claims. (Cl. 1214-38) This invention relates to servomotors and more particularlyto servomotors for the remote control of vehicles such as aircraft. s y An object of the invention is to provide a compact, simple and dependable servomotor of the above type.

Another object is to provide a servomotor which may be readily rendered inoperative when the control is to betaken over manually.

Another object is `to providea device of the above type which is automatically and promptly rendered operative when the manual control is terminated.

Another object is to provide a servomotor having novel and improved .details of construction and combinations of parts.

Variousand other objects and advantages will be apparent as the nature of the invention is more fully disclosed.

` The novel features which are believed to be characteristic of this invention will be pointed out more particularly in the claims .appended hereto. 'The invention itself may be better understood, howevenby referring to the following description, taken in connection with the accom panying drawing, in whichcertain speciilc ein loodiments thereof have beenset forth for purposes oi illustration. l

In the drawing,

3o Fig. l is a sectional view, partly diagrammatic,

o ci' a servomotcr embodying the present inven' tion; l I

Fig. 2 is a similar sectional view illustrating a` further embodiment of the present invention,

with the elements thereof in position for manual operation; and

l'iig. 3 is a similar sectional view of a part of the device otFig. 2, with the elements thereof in position for power operation.

am `l'tei'erring to the drawing, theiservomotor is shown in Fig. 1 as comprising a housing1 I having apair of operating cylinders 2 and 3 actuating a double-ended piston 4 having a piston rod 5 attached thereto whichis adapted to be connected to the mechanism controlled, such as the rudder, for controlling the operationof the vehicle. The 'pieton 4 is actuated by fluid pressure which is supplied hy conduits 6 and 1, communicating with the cylinders 2 and 3 respectively. 'Ihese'conduits 5` and I are in communication with supply conduits 8 and 9 which in turn communicate 'with a valve cylinder I0 having an inlet port Il closed by .a valve piston I2 and a pair of outlet ports I3 and I4 closed by valve pistons I5 and I6 respectively.I 'I'he valve pistons I2, I5 and I6 are mo H ted on a valve rod VIl which may be connected to the directional control device, not shown. The inlet port II is connected to a pipe 2D which connects through a valve 2l with a `fluid pressure supply pipe 22. Outlet ports I3 5 and I4 communicate with a chamber 23 which in turn is connected to a return or discharge pipe 2l.

In order to'eliminate thedrag of the piston 4 when the craft is to be controlledlmanually, 'a by-pass channel 28 is provided in the housing I 10 which interconnects the conduits 6 and 1. This lay-pass channel 28, lwhen open, permits free circulation oi the huid between the cylinders 2 and 3 so that the piston l may be freely moved by 'manual means. For/closing the by-pass channel l5 28 a valve 30 is provided which is normally` held open by a spring 3l The valve 30 communicates with a uid pressure `cylinder 32 to which fluid is supplied through a supply pipe 33 from a pipe 3l` communicating with the main supply pipe 22. 20

` A restriction 35 is provided in the pipe 3l torel duce the now through the pipe 34 for the purpose to -be described. The arrangement is such that liluid` pressure supplied to the cylinder 32 closes the valve 3l! against the action of spring 3 I there- 25 by separating conduits 6;. and l and placing the device in condition for remote control.

In order to release the fluid pressure on valve 30, a discharge line 39 m `prcwided having a valve 38 which is adapted, Whencpem'to permit the 30 fluid supplied through pipe 3B to be discharged through pipe 39 instead of building up pressure in the cylinder 32. The restriction 35' in pipe 34, however, reduces the ilow ci fluid under these conditions to a value such that the uid pressure 35 in the main supply line 22 is not appreciably reduced. I

l Suitable means may be provided for operating valve 2l and 38 in unison. In the form shown. these valves are connected by a link 40 which is 40 actuatedby a solenoid 6I so that when the valve 2l is closed the valve tt is opened, and when the .valve 2| is opened the valve 3B is closed.

In the position of the valves shown in Fig. l., the device isunder the act oi beingchanged over 45 from manual to remote control but valve 30 is shown in completely closed position. Solenoid 4I has been actuated to open valve 2l andto close valve38. It is the closure ci valve 38 that permits pressure Ato be `huilt up in the cylinder 50 32 from supply pipe 34, thereby closing valve 3l! and blocking by-pass channel 28. The opening oi' valve 2| permits uid pressure to be supplied through pipe 20 to valve cylinder I0. In the position shown, port Il is closed by valve piston 55 l2 and outletports i3 and i4 are closed by valve pistons l5 and i6. In this position 'no control eect is exercised and piston 4 will remain in its central position.

When control is to be eected to movethe piston 4 either to the right or to the left, the control mechanism is caused to move valve rod i1 to the right or left, as the, case may be. Move ment of this rod'to the right, for example, causes the valve piston i6 to uncover the outlet port i4 and to place the same in communication with channel 9 leading to cylinder 3. This same movement causes movement of valve pistons l2 and l5 to the right, places port ll in communication with channel 8, thereby supplying uid pressure to piston 2 and permitting the uid to be removed' from cylinder 3 through outletport lo and return pipe 24. This causes movement of piston 4 to the right, which continues until the pressures are equalized by returning valve rod l1 to its initial position.

Movement of valve rod i1 to the left effects a reverse operation, placing channel 8 in communication with outletport i3 and channel 8 in communication with inlet port il.

When the control is to be taken over manually, solenoid 4| is actuated to close valve '2| and to open valve 38. Closing valve 2i interrupts the fluid pressure supply to pipe 28. Opening valve 38 serves to bleed cylinder 32 through exhaust pipe 39, thereby reducing the pressure in cylinder 32 and permitting the valve 38 to open under the action of spring 3|. This opens by-pass channel 28 and permits free manual operation of the piston 4.

It is to be noted that the closing of valve 38 simultaneously with. or prior to the opening of i valve 2| prevents the pressure in pipe 20 from be cut out of operation and taken over" manually by means of the system above described without reducing the iluidpressure within line 22 and interfering with the operation of the other servomotors. Valves 2| and 38 are preferably so designed that when the device is shifted over to automatic operation the valve 38 is closed before the Valve 2| opens. This insures the closing of valve 30 before fluid pressure is supplied to servomotor valve cylinder U8.

In the embodiment shown in Fig. 2, the various control valves are formed in a unitary structure. In this embodiment, afhousing 45 is provided having cylinders 46 and 41 formed therein cooperating with a double-ended piston 48 connectedto a piston rod 48 by whichgthe control is eifected. Cylinders 48 and 41 connect through channels 58 and 5i with a valve cylinder 52, thence through channels 53 and 54 with a valve cylinder 55. Y

tThe valve cylinder 55 contains valve pistons 56, 51 and 58 controlling respectivelyoutlet port 59, inlet port 60 and outlet port 6|. The outlet ports 59 and 6| communicate through .a chamber amarre 62 with an outlet or return pipe 64. Inlet port 6@ is connected by a conduit 65 to a port 66 in valve cylinder 52. The source of uid pressure is connected to a channel 61 in the housing 45 which communicates with valve, cylinder 52 through a port 68. Valve pistons 56, 51 and 58 are mounted on a valve md5@ which'is connected to the control apparatus, not shown.

A valve rod 18 is slidably mounted in valve cylinder 52 and carries; a piston 1| adapted to vengage the end of valve cylinder 52 for limiting the movement of valve rod 10; a piston 12 adapted to close the communication between the'channels 58 and 5i through valve cylinder 52 when 'the valve rod 'lll is in its left-hand position; a piston 13 serving as a guide element; a piston 14 adapted to prevent communication between ports to and 88 when valve rod 10 is in its right-hand position and to permit such communication when valve rod 1|) is moved to the left; and a piston 15 adapted to receive uid pressure from a chamber 16 which communicates through a restricted port 11 with supply channel (il. The arrangement is such that pressure within chamber 18 acting on piston 15 causes valve rod 18 and associated pistons to move to the left-hand position, which is the position for remote operation of the control mechanism by means of the servomotor. `When the pressure within chamber 16 is released, a spring 18 moves valve rod 18 to the right, which is the position as shown in Fig. 2 and which is the position for manual operation.

For controlling the pressure within the chamber 16, a discharge port 8U is provided which is closed by a pin 8| controlled by a solenoid 82. The discharge port communicates with a chamber 83 which is connected by a pipe 84 to the discharge or return pipe 64. n

With the parts as shown in Fig. 2, this embodiment is adapted for manual operation of the l control mechanism. In this position the solenoid 82 is deenergized. The pin 8| is retracted from discharge port 80. Pressure in chamber 16 is reduced by'leakage of the fluid through discharge port 80 and thence through pipe 84 to return pipe 64. Valve rod 10 is in its right-hand position in which piston 14 shuts oil" communication between supply channel 61 and pipe 65, thereby releasing the pressure on the servomotor control, and piston 12 is at the right, thereby establishing communication between the channels 58 and 5|, which serve to by-pass cylinders 46 and 41. lThe servomotor is accordingly rendered inoperative and piston 48 may be manually operated.

ln changing over to remote control, solenoid 82 is energized, thereby causing pin 8| to close port 88 as shown in Fig. 3. 'I'his permits pressure to build up in chamber 16 which acts against piston 15 to shift valve rod 10 to the left. This movement of the valve rod rst causes piston 14 to close port 66 and does not establish communication between port 66 and port 68 until the valve rod has moved a suilicient distance so that piston 12 has passed the channel 5|, as shown in Fig. 3, thereby interrupting the bypass between channels 50 and 5| through valve cylinder 52. Pressure is then applied through pipe to the valve cylinder 55 which is adapted to control the position of piston 48 in response to a suitable actuation of the valve rod 69.

In the above described system it is to be noted that the control valves may be actuated from a remote point such as the pilots seat of an aircraft and that several servomotors may be actuated in unison from the same source of fluid pressure. Valves 2l" and 38 in Fig. l or the corresponding elements in Fig. 2 may be con- 5 nected to actuate a plurality `of servomotors, if desired. In the embodiment of Fig. 2, the by-pass channels of several servomotors may be shut off Adue to displacement of the valve rod 'Ill by the use of suitable pistons.` Theconstruction is accordingly adapted to permit the connecting or disconnecting of several servomotors either collectively or independently, inasmuclr as the disconnecting of one servomotor does not disturb the pressure supplied to the other servomotors. i

It is to be understood that the throttle restriction 35 of Fig. 1 may be disposed in pipe 39, if desired, in which case it must be suitably designed to release the pressure within control 20 cylinder 32 without reducing the pressure on the line.

Furthermore, the device may be so arranged that the discharge channel may be shut off instead of the by-pass channel, and it is to be understood that various types of servomotors, either hydraulically or pneumatically driven, may be substituted for the embodiment shown herein.

Although certain specific embodiments have been shown for purposes of illustration, it is to be understood that the inventionis capable of `various uses and that various changes and modications may be made` therein as will readily appear to aperson skilled in the art. The invention isto be limited vonly in accordance with the following claims.

What is claimed is: 1. A servomotor, comprising Va control member, `a cylinder having a pair of pressure fluid chambers reversibly actuating said control member. a pressure fluid supply line supplying fluid `under pressure to said chambers, a pressure fluid by-pass interconnecting said chambers and adapted, when open, to permit free operation of said control member, a fluid pressure actuated valve closing said by-pass, means supplying fluid under pressure from said supply line to actuatesaid valve, means controlling said supply of fluid, means controlling the supply of fluid to said chamber, and means for simultaneously operating said control means to cut off the supplyvof said pressure fluid to said chambers when said valve is actuated towards open position.

2. A servomotor, comprising a control mem.- bera cylinder having a pair of pressure fluid chambers reversibly actuating said control member, a pressure fluid supply line Supplying fluid pressure to saidy chambers, a pressure fluid bypass interconnecting said chambers and adapted, when open, to permit free operation of said control member, a fluid pres-sure actuated valve closing said by-pass, means supplying fluid'under pressure from. said supply line to actuate said valve, means controlling the supply of fluid to said chambers, means controlling the supply of fluid to said valve, and'means for timing the operation of both said means whereby fluid pressure is supplied to said valve for closing the same prior to the restoration of pressure fluid to said chambers. 70 3. Aservornotor, comprising a control member,

. a cylinder having a pair of pressure fluid cham.-

bers reversibly actuating said control member, a pressure fluid supply line supplying fluid under pres"ure"to saidch'ambers, a pressure fluid bypass interconnecting said'chambers and adapted,

' said chambers.

4. A servomotor, comprising a control member, a cylinder having a pair of pressure fluid chambers reversibly actuating said control member, a

pre'sure fluid supply line supplying fluid under pressure to said chambers, a pressure fluid bypass interconnecting said chambers and adapted, when open, to permit free operation of said control member', a fluid pressure actuated valve closing said by-pas, a passage supplying fluid under pressure from said'J supply line to actuate said valve, means to release the pressure in said passage for opening said valve, said passage having a restriction adapted to limit the passage of fluid therethrough whereby the release of pressure on said valve is prevented from affecting the fluid pressure in said supply line. x

5. A fervomotor, comprising a control member, a cylinder having a pair of pressure fluid chambers reversibly actuating said control member, a pressure fluid supply line supplying fluid under pressure to said chambers, a pressure fluid by-pass interconnecting said chambers and adapted, when open, to permit free operation of said control member,r a fluid pressure actuated valve closing said bypass, a passage having a restriction through which fluid is supplied to said valve to actuate the same, and 'control means in said passage behind said restriction to release the fluid pressure on said valve for opening the same. f

, 6. A servomotor, comprising a control member, a housing provided with a cylinder having a pair of pressure fluid chambers reversibly actuating said control member, a valve cylinder in said housing having a control valve therein to control the supply lof fluid to said chambers, a

pressure fluid by-pass formed in said housing and said control member, a valve cylinder in said housing having a control valve therein to control the supply of pressure fluid to said chambers, a pressure fluid by-pass formed in said housing and interconnecting said chambers, a valve for closing said by-pass, fluid pressure means actuating said valve, means to interrupt the supply of fluid tosaid valve cylinder, said last means being mechanically interconnected with said bypass valve whereby, when said valve is closed, pressure fluid is supplied to said valvecylinder for reversibly actuating said control member and when said valve is open the supply of pressure fluid to said "control cylinder is interrupted, means controlling the supply of pressure fluid to said valve, and electromagnetic means controlling said last means.

8. A servomotor, comprising a control member, a cylinder having a pair of pressure fluid chambers reversibly actuating said control member, a pressure fluid supply line supplying fluid-under pressure to said chambers, apressure fluid bypass interconnecting said chambers and adapted, when open, to permit free operation of said control member, a lluid pressure actuated valve closing said by-pass, means supplying fluid under pressure from said supply line to actuatesaid valve, control means to control the pressure on said valve, control means to control the supply of iiuicl from said line to said chambers, and means interconnecting both of said control means for operationin unison whereby the supply of fluid to said chambers is prevented except when said valve is closed.

9. A servomotor, comprising a control member, a cylinder having a pair of pressure fluid chambers reversibly actuating said control member, a pressure fluid supply line supplying fluid under pressure to said chambers, a pressure iluid by pass interconnecting said chambers and adaptto operate in unison whereby fluid is supplied to said chambers only'when said by-pass valve is closed. I

10. A servo-motor comprising a control member, a housing provided withA a cylinder having a pair of pressure iluid chambers reversibly actuating said control member, a valve cylinder in said housing having a control valve therein to control the supply of fluid to said chambers, a

pressure fluid by-pass formed in said housing andinter-connecting said chambers, means closing said by-pass, means responsive to fluid pressure for controlling said closing means, and means to interrupt the supply of fluid to said valve cylinder, said last two means comprising a plurality of pistons mounted on a common piston rod movable in said by-pass.

' 11. A servo-motor comprising a control member, a housing provided with a cylinder having a pair of pressure fluid chambers reversibly actuating said control member, a valve cylinder in said housing having a control valve therein to control the supply of iluid to said chambers, a cylinder providing a by-pass-interconnecting said chambers, a piston slidable in said by-pass cylinder for closing said by-pass, a valve port leading from said by-pass cylinder to the inlet of said control valve, an inlet to said by-pass cylinder,

' and a piston slidable in lsaid by-pass cylinder pass cylinder ior closing said by`pass, a second piston mounted on said piston rod, a restricted orifice" leading from said' pressure fluid source to said second piston, and electro-magnetic actuated means controlling the pressure on the outside of said oriilce.

EDUARD FISCHEL. JOHANNES THIRY. 

